Berkeley
held that no one has experienced such matter firsthand and, further, that such a theory is
a conception of mind. Berkeley thought that people made a common error in assuming
that such objects as trees, houses, and dogs exist where there is no mind to perceive them.
Instead, to say that a thing exists means that it is perceived by some mind—esse est percipi
(to be is to be perceived). To the classic question “Does a tree falling in the middle of a
forest make a sound if no one is around to hear it?” Berkeley would answer “No, if we rule
out the idea of it being perceived by God.” There is no existence without perception, but
things might exist in the sense that they are perceived by a Supreme Being